1. Field of the Invention
The present invention relates to an S-cam brake assembly and more specifically to an S-cam brake assembly wherein spacer means are provided to adjust the relative position of the S-cam and the spider member and the relative position of the brake shoes and the spider member to allow the brake assembly to vary the distance from the axle mounting face to the brake centerline. The retaining spring means is connected to the web of each of the brake shoes and extends around the anchor pin for biasing the brake shoes toward each other through the anchor pin. The shoe retaining spring means is also spaced inwardly in a radial direction from the shoetable of the brake shoes to thereby shield the shoe retaining spring means from the heat generated when the vehicle is braked.
2. Background of the Invention
S-cam brakes are known in the art. In most of the known S-cam brakes the offset, i.e., the distance measured from the axle mounting face to the brake centerline, is fixed. This requires a unique casting and machining combination for each individual offset which is desired. This results in higher manufacturing and warehousing costs than if a simple S-cam brake were provided which would have variable offsets.
The brake shoe retaining springs utilized in the prior art do not simultaneously provide for easy removal of brake shoes from the brake and for mounting of the springs away from the heat generated by the brake shoes and brake drum. The heat generated between the friction surfaces and the brake drum has an adverse affect on spring life. The known shoe retaining springs which are mounted away from the heat generating friction surface and brake drum do not extend around the anchor pin. Hence, the known retaining springs bias one end of each of the brake shoes against the anchor pin through a moment arm which is determined to be the distance between the point of attachment of the retaining springs and the point of engagement of the brake shoes with the anchor pin assembly. Such a known construction makes shoe removal from the brake mechanism difficult due to the forces exerted on the brake shoes by the springs through the moment arm against the anchor pin.